Spring.



H. F. THUR-STON. SPRING. APPLICATION FILED MAR. 30. I914.

- 1,158,870. Patented Nov. 2, 1915.

km aw I I Inv gtbm @Q\%%Qw- WM Atty.

are.

SPRING.

Application filed March 30, 1914. Serial No. 828,158.

To all whom it may concern:

Be it known that I, HOWARD F. THURSTON, of Newry, in the county of Ogzford and State of Maine, have invented certam new and useful Improvements in Springs, of which the following is a specification.

My invention relates to elliptical or other like springs having overlapping leaves.

It is a well known fact that the several leaves of such springs when in use have a sliding movement, one on another and the friction between the sliding faces has. a tendency to make the spring much more stiff than it would be if the leaves were free. This is particularly true when the contacting surfaces of the spring become rusty or when paint works in between them.

Efforts have been made to overcome this fault by inserting antifriction rolling members between the leaves of the springs, the rolling members being confined in cavities cut out from the under side of the leaves.

The difiiculty in the construction last mentioned is that a cavity cut from the under side of the spring, particularly nearthe end where the leaf is thin removes a considerable portion of the metal of the leaf, thus weakening the spring at its weakest point. The cutting away of the material of the spring at or near its endweakens a spring made on this principle more than it would the ordinary spring. The reason is that when the balls or rollers are inserted in the cavity the bearing pressure for that end of the leaf rests on the balls and on the bottom of the cavity, instead of being distributed over the whole surface of the leaf as it would be in an ordinary spring where the leaves rest closely in contact with each other.

Aside from the weakening of the spring the expense of cutting such cavities is considerable as they must be cut by a milling machine or other similar cutting mechanism.

According to my invention I form the cavity for receiving the rolling members in the under or contact side of the leaf beyond the end of the next overlapping leaf when there is one, by striking'up the metal of the leaf and inserting into said cavity one or more rolling members.

The result is that I not only do not Weaken the leaf but by raising the boss or projection on the top of the leaf I strengthen it at this point. This is important because of the extra strain on the leaf when it is lifted up Specification of Letters Patent.

Patented Nov. 2 1915.

by the ballsv and made to bear at a single point as above pointed out.

The expense of forming the cavity is reduced to a very trifling amount because all 1t is necessary to do is to strike up the metal on the under side while red hot with a suitable die.

A boss or offset is formed on the upper side of the leaf which does notinterfere wlth the action of the spring as it is beyond the end of the next higher leaf when there is an over-lapping leaf. The cavity is made slightly shallower than the ball so that there is a space preferably about {5 inch left between the adjacent surfaces of the leaves.

My invention is easily applied to old springs as well as new by drawing the temper on the ends of the leaves where temper is not essential as it is in the body of the leaf and stamping the recess with a suitable die.

I have illustrated in the accompanying drawing an elliptical spring provided with rolling members between its leaves according to my invention. Figure 1 is a side view of a common form of elliptical spring having my ball bearings applied thereto, Fig. 2 is a longitudinal section through one of the cavities, and Fig. 3 is a cross section showing two of the cavities side by side.

The spring is. shown as being made up of a lower leaf 0 and overlapping leaves 6, c, and 03. In the under side of each of the leaves is formed a cavity so proportioned as to contain one of the balls f. The cavity is struck up from the under side by a suitable die and raises a boss or projection e on the upper surface of the spring leaf. The cavity is somewhat elongated lengthwise of the spring so as to allow the ball to roll freely within narrow limits as the leaves of the spring move one over the other. I have here shown two cavities on each leaf side by side but it is obvious that I may use one or more than two and that I may form them to re ceive rollers as well as balls. I have shown asingle ball in each recess but it is evident that more than one ball may be used.

The halls may be easily replaced by simply forcing the ends of' the leaves apart far enough toremove the. old ball and insert the new one.

A spring constructed according to my invention' is exceedingly easy in its action; it may be cheaply made; the balls may be easily renewed and when applied to automobiles it increases the easy riding qualities to avery great extent.

In the specification and claims I have used the term under to indicate the bearing or contact face of the leaf and the term upper to indicate the free face but it is obvious that When the spring is inverted the upper would become the under and vice versa.

1 claim 1. A spring composed of a plurality of superimposed leaves of gradually decreas ing lengths, each leaf being struck up at each end to form an elongated cavity on its under side and a strengthening rib on its upper side, each cavity and rib being arranged beyond the respective ends of the next overlying leaf, and a rolling member loosely mounted in each cavity. 2. A spring composed of a plurality of superimposed leaves of gradually decreasing lengths, each leaf being struck up at each end to form a pair of oppositely disposed elongated cavities on its under side and a pair of elongated strengthening ribs on its upper side, the cavities and ribs at each end of each spring being arranged beyond the ends of the next overlying leaf, and a rolling member mounted in each cavity.

In testimony whereof I have affixed my signature, in presence of two Witnesses.

HOWARD F. THURSTON. WVitnesses VIVIAN THURSTON, P. iL VVEYMOUTH.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents.

Washington, D. C. 

